Fuel cells are classified into various types in accordance with the kind of an electrolyte or the kind of an electrode. Typical examples are an alkali type, a phosphoric acid type, a molten carbonate type, a solid electrolyte type and a solid polymer type. Among them, the solid polymer type fuel cell capable of operating at a temperature of from a low temperature of about −40° C. to about 120° C. has been in the spotlight, and recently, the development and practical use thereof has been advanced as power sources having low environmental pollution used in automobiles. Driving sources for cars and fixed electric sources have been studied as the use of the solid polymer type fuel cell. In order to the cells to these uses, they are demanded to have durability for a long period of time.
The solid polymer type fuel cell has a form such that a polymer solid electrolyte is sandwiched between an anode and a cathode, a fuel is fed to the anode while oxygen or air is fed to the cathode and thereby oxygen is reduced in the cathode to produce electricity. Hydrogen, methanol or the like is mainly used as the fuel.
Conventionally, in order to enhance the reaction rate of a fuel cell and enhance the energy exchange efficiency of a fuel cell, a catalyst-containing layer (hereinafter sometimes referred to a catalyst layer for fuel cells) is provided on the cathode (air electrode) surface or the anode (fuel electrode) surface of a fuel cell.
As this catalyst, noble metals are generally used and further among the noble metals, platinum, which is stable at a higher electric potential and has high activity, has been used. As the carrier, which supports the catalyst metal, carbon has been used conventionally.
The catalytic ability of the carrier carbon can be enhanced only by increasing the specific surface area thereof. Therefore, the particle diameter of the carrier carbon needs to be diminished. However, the diminishing of the particle diameter of the carrier carbon has the technical limits. The catalyst obtainable by using the carrier carbon cannot secure sufficient catalytic ability.
Furthermore, the carbon has low heat resistance, and the carrier carbon corrodes and disappears with running the reaction in a fuel cell, so the catalyst metal particles such as Pt and the like which are supported on the carrier carbon are liberated from the carrier to cause a phenomenon such that the catalyst metal is flocculated. As a result, the effective area is lowered and the cell ability is also lowered.
In order to solve this problem, Patent document 1 discloses an electrode catalyst layer of a fuel cell which corrosion resistance is enhanced by thermally treating a carrier carbon at a high temperature (Patent Document 1).
However, there is no change in the structure that platinum and the like are directly supported on the carbon carrier, which suffers corrosion and disappearance in the noble electric potential environment, so the corrosion resistance is not vastly improved even by the above technique.    Patent Document 1: JP-A-2002-273224